1. Field of the Invention
The present invention relates to an ink-jet recording apparatus and, more particularly, to an ink-jet recording apparatus having an ink storage means and a liquid gauge (to be referred to as a manometer hereinafter) communicating with ambient air.
2. Related Background Art
Various types of ink-jet recording apparatus are known as recording apparatuses using liquid ink as the recording material. In an arrangement proposed for such apparatuses, the remaining amount of ink as the recording material is detected, as in apparatuses of the other types.
FIG. 1 shows a conventional arrangement for detecting a remaining ink amount in a removable ink cartridge 1 for storing recording ink. An ink flow path 1a extending from the ink cartridge 1 guides ink I from the cartridge 1 to a cylindrical upright manometer 2 by gravity and the ink I in the manometer 2 is supplied to an ink-jet printing head (not shown) therefrom. The upper end (and its vicinity) of the manometer 2 is open and communicates with ambient air. Therefore, the liquid level of the ink I in the manometer 2 coincides with that in the ink cartridge 1.
Thus, when two electrodes 3 are vertically aligned in the manometer 2 and a resistance thereacross is detected, the remaining amount of the ink cartridge 1 can be detected. At least the upper electrode 3 is arranged at such a position that it can detect the remaining amount when a predetermined amount of ink is remaining in the cartridge 1.
With the above arrangement, however, since the upper end of the manometer 2 is open, if the ink cartridge 1 is removed so that it can be changed, ink leakage can occur from ink flow paths of the printing head side or the cartridge side, or from the opening of the manometer 2, thus soiling the interior of the apparatus or short-circuiting the internal circuit.
Furthermore, with the above arrangement, when the amount of remaining ink of the ink cartridge 1 reaches a predetermined value, cartridge change is performed. In this case, the ink liquid level on the manometer 2 is decreased to a position indicating that it contains little remaining ink, and at least one electrode 3 is exposed from the ink surface.
When the cartridge 1 is changed, the ink I flows into the manometer 2 from the ink cartridge 1 through the flow path 1a by natural falling, and the ink levels in the cartridge 1 and the manometer 2 become equal to each other. Conventionally, however, since ink is supplied from a new cartridge into the manometer 2 by gravity, it takes some time before the liquid levels become equal, and some times the apparatus is caused to enter an alarming state, representing the little remaining ink, is caused by erroneous detection and continues even after cartridge replacement.
When the ink cartridge is removed for replacement, the atmospheric pressure acts on the ink in the manometer, and ink leakage can thus occur from the ink flow paths of the printing head side or the cartridge side, thus soiling the interior of the apparatus or short-circuiting the internal circuit. If the apparatus is inclined during change, ink may overflow from the opening of the manometer.